#include <stdio.h>
#include <assert.h>

// You turn off the check by defining the macro NDEBUG.
// gcc -D NDEBUG -D HELLO=3 compile_macro.c
int main(int argc, char const *argv[])
{
    assert(NULL);

#ifdef HELLO
    printf("macro hello define as %d\n", HELLO);
#else
    printf("macro hello not defined");
#endif

    return 0;
}
